Traditional twisted-pair telephone lines can be used to provide voice telephone service to customers. A central office can connect to a user premises via a telephone line, such as a twisted-pair copper line. Once at the user premises, the telephone line may connect to customer wiring within the customer premises. The customer wiring may split into more than one branch, and it may run to various different locations within the customer premises. Plain old telephone service (“POTS”) devices, such as analog telephones, can connect to the customer wiring. Through the customer wiring the POTS devices can interface with the central office and ultimately communicate with other devices also connected to the telephone network.
In additional to carrying voice calls, a telephone line can also carry data. For example, computers, fax machines or other data devices can connect with the customer wiring, and through the connectivity provided by the central office, they can communicate with other data devices on the telephone network. In this type of configuration, the data is transmitted over the bandwidth generally allocated for voice calls. The bandwidth for voice calls is generally limited, and this also limits the data transmission rate. Additionally, a traditional telephone line generally cannot support simultaneous data and voice transmissions.
XDSL is a technology that overcomes some of the limitations of POTS service. The acronym XDSL generally identifies the broad class of “digital subscriber line” services. The letter “X” in the general acronym can be replaced with another letter to identify a specific type of digital subscriber line service, such as asymmetric digital subscriber line (“ADSL”) service or high-bit-rate digital subscriber line (“HDSL”).
Using XDSL, the bandwidth of the telephone line can be extended to support higher speed data communications. For example, by changing bandwidth-limiting filters on the telephone network, the overall available bandwidth for a telephone line connected to a customer premises can be increased. A portion of the available bandwidth can be used to support POTS services, such as voice calls. Another portion of the bandwidth can be used to support higher speed data communications. Other techniques, such as echo cancellation, can also be used to increase the data communication rate.
Various problems may occur within an XDSL transmission system. For example, in order for an XDSL transmission system to function properly, POTS devices located on the customer premises should be electrically isolated from the XDSL devices through the use of in-line filters. A POTS device not using a filter may adversely affect the data transmission rate of the XDSL devices. In another example, physical problems with the customer premises wiring or the telephone lines may develop.
When these problems occur, XDSL customers may make a service request to their XDSL service provider to diagnose and correct the problem. The service provider may be able to remotely isolate the customer premises equipment and wiring from the network-owned equipment and wiring, and then the service provider can test the telephone line from the network demarcation to the central office. This method may detect a problem on the network-owned equipment or wiring, but it would not detect a problem in the customer wiring. If a problem developed on both the network wiring line and the customer premises, this method would not be able to detect both problems.
Alternatively, the service provider can make an on-site service call to the customer premises. At the customer premises, a service technician can connect one or more test devices in order to test the telephone lines linking the customer premises and the central office. Once at the customer premises, the service technician can also test the customer wiring. This method could diagnose problems both with the telephone line and with the customer wiring; however, it has several disadvantages.
On-site service calls can be expensive. They require the service technician to travel to the customer premises, and they require time to connect the test equipment and to diagnose any problems. Often times, the responsibility for problems with the telephone lines are placed on the service provider, while the customer pays the costs for any problems relating to the customer wiring. Therefore, placing a service call in order to diagnose a problem on the customer premises, such as not installing an in-line filter on a POTS device, is not cost-effective for the customer.
In addition to cost, there are other disadvantages to diagnosing problems in this manner. For instance, there may be a significant delay between the time a customer places a service call and the time the service technician arrives at the customer's premises. This may cause the customer to be without XDSL service, or to have impaired XDSL service, while the customer waits for the service call to be performed.
Therefore, there exists a need for a better way to perform diagnostic testing in an XDSL system.